From German Patent No. DE-OS 19 24 002, there is known a welding torch, including a consumable electrode for arc welding, which includes a housing and a collet for a contact tube free of any thread. In the known torch, a threadless contact tube is fabricated from a tube having a circular contour, which is surrounded by a collet, which collet is in turn operatively secured to a housing for the collet. The housing for the collet is mechanically rigid with a gas nozzle, which gas nozzle is in turn connected by means of a thread to a pipe end by rotation of the gas nozzle, so that the contact tube is firmly clamped to the collet housing. A contact tube, free of any thread, is advantageous as far as manufacture and replacement of the contact tube is concerned, compared to devices of the prior art. The complicated arrangement of the housing for the collet, as well as the inadequate dissipation of heat from the contact tube, is disadvantageous, however.
In torches of the prior art, contact between the contact tube and the collet is maintained only through a few circumferential contact lines between the collet and the tube, so that any heat exchange from the contact tube to the pipe end of the torch can only be achieved through these few contact lines.